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Old 12-20-2019, 03:21 PM   #1
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Generator auto shutdown issue

The generator is an Kohler 8EOZ 8kw generator. It autoshutdown on me during a weekend cruise and decided to troubleshoot when I got home. Did the troubleshooting. If you don't know this generator, it is a mechanical one. But there are a series of electical shutdown features from 3 different sensors....oil pressure, coolant temperature, and exhaust temperature. When an autoshutdown is triggered, it lights a series of LED lights on the backside of the control circuit panel to alert you to what is causing the shutdown. You then follow a stupid flow chart in the maintenance manual to come to your conclusion on what is causing the shutdown. In every possible scenario, it was a control board failure that was causing the shutdown. So I replaced the control board. No joy! I then figured since the separate sensors were relatively cheap, I did the shotgun approach and ordered all 3. I put on the oil pressure one and the exhaust temperature one. The water temperature one was the wrong one so still haven't replaced that one but still....No joy on the other two!!! I have my serious doubts that the water temp sensor is the culprit.

If in fact the water temp sensor is not the cause, I guess the only place to go next is the actual oil pump??? I would find a way to put a mechanical gauge onto the oil pressure sensor "tap/hole" and see if there is in fact no oil pressure. Is there a way to bypass the oil pressure sensor to allow the engine to run for longer than the 3-5 seconds it runs before shutdown?

Anyway...open to any and all suggestions/advice. I have shotgunned about $450 bucks so far in parts and am not getting a solution. It may be important to note that the 12v circuit breaker does pop/open simultaneously upon auto shutdown. I have even tried holding/forcing that breaker in to see if it related to the autoshutdown...but the generator quit anyway.

At a loss....
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Old 12-20-2019, 04:00 PM   #2
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The sensors are bypassed for some number of seconds before they come into play because initially there's no oil pressure. It would be helpful to know how long that bypass time is supposed to be.

Ted
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Old 12-20-2019, 04:04 PM   #3
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John,

You should be able to simply pull the wire from the OP switch to bypass it. It is a NC switch that in operation, grounds to the block when no pressure is present, it's the same as the two other alarm sensors.

When you press the start switch, a 12v run solenoid is also energized, effectively bypassing the alarm/shutdown circuits while the engine is starting. Once started, the alarm/shutdown circuits are active and keep the run solenoid energized unless a fault condition is sensed. The control board also senses 120VAC from the generator which if not present, will not allow the generator to run.

To check the oil pressure, remove the OP switch and install a manual gauge in its place. Then start the generator holding the pump shutdown lever in the run position long enough to test the pressure.

BTW, I have a manual test gauge on a flexible hose with a Yanmar adaptor if you need it.

Your generator is almost identical in operation to the Kohler I had to troubleshoot on Boomarang
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Old 12-20-2019, 04:36 PM   #4
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Don't know your engine, but they usually have a fuel solenoid that moves the fuel lever on the injector pump. A spring moves the lever to off when the coil isn't energized. Usually there are 3 leads, common (-), start (pull in coil - higher amperage), and hold (low amperage). When you push the start button, the pull in coil controls fuel. When the start button is released, the hold coil keeps the fuel lever on. If the engine quits when releasing the button, the fuel solenoid could have a bad hold coil or whatever controls the coil.
If you can start the engine while looking at the injector pump lever, hold the lever by hand before releasing the start button. It won't bite. The engine should continue to run.

To install a mechanical oil pressure gauge, you should be able to install a tee where the current sensor is. That way you can have both a gauge and sensor.
The 12v breaker opening could indicate some short. Could be in the fuel solenoid. Wiring diagram would be handy.
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Old 12-20-2019, 05:27 PM   #5
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Ted, the manual says 5 seconds although I do not think it is even running that long.

Larry, maybe I might take you up on your offer. It is a Yanmar engine....

Lepke, thanks . Good advice. I am thinking this might be an electical issue. The breaker is a small breaker, 5 amps I think, and it is tripping due to overamperage. Sadly I think I left that out...I left that out in my head because I thought the breaker popping was all part of the shutdown sequence. But the more I think about it....the more that is a possibility. Sooooo my question would be what could cause overamperage to that breaker?
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Old 12-20-2019, 06:00 PM   #6
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Had a similar problem years ago on an old Onan MDKD, problem turned out to be a plugged heat exchanger.
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Old 12-20-2019, 06:05 PM   #7
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I had a Kohler 7.5kw on my Carver C34. For two years the Kohler techs worked on that thing but never fixed it. When at anchor it acted like the starting battery was dead. Replaced the battery but no go. They replaced a lot of things but never fixed it.
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Old 12-20-2019, 06:08 PM   #8
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Ted, the manual says 5 seconds although I do not think it is even running that long.

Larry, maybe I might take you up on your offer. It is a Yanmar engine....

Lepke, thanks . Good advice. I am thinking this might be an electical issue. The breaker is a small breaker, 5 amps I think, and it is tripping due to overamperage. Sadly I think I left that out...I left that out in my head because I thought the breaker popping was all part of the shutdown sequence. But the more I think about it....the more that is a possibility. Sooooo my question would be what could cause overamperage to that breaker?

The 5 amp breaker is the control power circuit. Something is grounding out. Disconnect and bypass the trips one at a time. Check the contact operation with a DVM. Make sure you don't have a loose wire flopping around on the machine.
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Old 12-20-2019, 06:11 PM   #9
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Have you tried starting with all of the AC load breakers open or on Shore power? With no electrical load the only way for overload is a generator fault or bad breaker.
I have a manual rotary switch. So there is no AC load when starting. My question reference "overload" is a DC overload to the teeny tiny little 5 amp breaker that pops along with the shutdown. It is difficult to tell if that is what is causing the shutdown or if it is part of the shutdown sequence(which is what I initially thought but now have my questions...)....
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Old 12-20-2019, 06:17 PM   #10
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I have a manual rotary switch. So there is no AC load when starting. My question reference "overload" is a DC overload to the teeny tiny little 5 amp breaker that pops along with the shutdown. It is difficult to tell if that is what is causing the shutdown or if it is part of the shutdown sequence(which is what I initially thought but now have my questions...)....
The 5 amp breaker should not trip except on an electrical fault. It did not trip before did it?
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Old 12-20-2019, 06:22 PM   #11
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I have a manual rotary switch. So there is no AC load when starting. ...
Well there could be if the transfer switch is left in GEN while trying to start. Bad for many reasons. Should always be started in SHORE or OFF position.
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Old 12-20-2019, 06:23 PM   #12
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Quote:
Originally Posted by Baker View Post
The generator is an Kohler 8EOZ 8kw generator. It autoshutdown on me during a weekend cruise and decided to troubleshoot when I got home. Did the troubleshooting. If you don't know this generator, it is a mechanical one. But there are a series of electical shutdown features from 3 different sensors....oil pressure, coolant temperature, and exhaust temperature. When an autoshutdown is triggered, it lights a series of LED lights on the backside of the control circuit panel to alert you to what is causing the shutdown. You then follow a stupid flow chart in the maintenance manual to come to your conclusion on what is causing the shutdown. In every possible scenario, it was a control board failure that was causing the shutdown. So I replaced the control board. No joy! I then figured since the separate sensors were relatively cheap, I did the shotgun approach and ordered all 3. I put on the oil pressure one and the exhaust temperature one. The water temperature one was the wrong one so still haven't replaced that one but still....No joy on the other two!!! I have my serious doubts that the water temp sensor is the culprit.

If in fact the water temp sensor is not the cause, I guess the only place to go next is the actual oil pump??? I would find a way to put a mechanical gauge onto the oil pressure sensor "tap/hole" and see if there is in fact no oil pressure. Is there a way to bypass the oil pressure sensor to allow the engine to run for longer than the 3-5 seconds it runs before shutdown?

Anyway...open to any and all suggestions/advice. I have shotgunned about $450 bucks so far in parts and am not getting a solution. It may be important to note that the 12v circuit breaker does pop/open simultaneously upon auto shutdown. I have even tried holding/forcing that breaker in to see if it related to the autoshutdown...but the generator quit anyway.

At a loss....
Are you getting steady fuel supply?
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Old 12-20-2019, 06:59 PM   #13
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vkec timing

i have westerbeke not the same but my distributor loosened but ran great but ran rich and exhaust sensor shut here down
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Old 12-20-2019, 07:12 PM   #14
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Have you talked to the PO? How was the genset survey? You just bought, it may not be a "new" issue.
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Old 12-20-2019, 07:41 PM   #15
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I have a 6.5 Kohler that did auto shutdown. While waiting for the local generator guru to come look at it I had it hauled out for bottom paint. Had some other work to do by my mechanic who worked on the boat for 6 years with PO. I commented about the generator in passing. He said bet it needs coolant that it had it happen a couple of times before. Added maybe a pint and voila. Runs like a top.
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Old 12-20-2019, 07:51 PM   #16
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When it failed on your trip, had it been running for a while? Sounds like now it only runs till the bypass circuit drops out.

Ted
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Old 12-20-2019, 08:10 PM   #17
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I have a NL 6kw. No instrumentation at all. Basically it was said, dont worry, the NL will protect itself. That was all well and good until it started shutting down after pithing 5 minutes, loaded or unloaded. Turned out to be a defective water temp sensor. I have now added an oil pressure gauge, coolant temp gauge and an overboard high temp alarm. I do believe I am 'covered'.
Ah, replaced the exhaust elbow. It was made up of some sort or cast iron. Turns out NL knew of the cast iron elbow problem. The new elbow is made up of an aluminum alloy. Sadly, the NL folks decided not to contact the owners' nor provide a free elbow upgrades.
Ah, time on the generator, less than 100hrs. A valid reason for a fresh water flush if not running the generator once a week. The cooler was checked and it was okay.
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Old 12-20-2019, 10:42 PM   #18
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I think you are a more skilled mechanic than I am Baker, so take this for what it is worth. I also have an 8EOZ, which started behaving similarly last year when the controller went bad. I know you said that you replaced the controller, but you also said that you have spent $450 in parts including the sensors, which is throwing me off because the controller for an 8EOZ is about $900.


I got an error code for "overspeed" when my controller went bad. Is that what you saw as well?


BTW, I ended up finding a controller on ebay for $500, new in the box. If that is the issue it may be worth a look.
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Old 12-20-2019, 10:53 PM   #19
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Have you talked to the PO? How was the genset survey? You just bought, it may not be a "new" issue.
This is the Carver....the "old" boat. It has served well for the past 6.5 years.
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Old 12-20-2019, 10:57 PM   #20
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I think you are a more skilled mechanic than I am Baker, so take this for what it is worth. I also have an 8EOZ, which started behaving similarly last year when the controller went bad. I know you said that you replaced the controller, but you also said that you have spent $450 in parts including the sensors, which is throwing me off because the controller for an 8EOZ is about $900.


I got an error code for "overspeed" when my controller went bad. Is that what you saw as well?


BTW, I ended up finding a controller on ebay for $500, new in the box. If that is the issue it may be worth a look.
I have a firend I am working with and he said he got a controller for $300??? ANd then the sensors were $150 total. THe dude is very honest and quite skilled...but not electrically....and neither am I. We went through the flow chart in the manual and it turned up the controller every time. But that did not fix it. I guess I need to ask him if he went Chinese or after market I guess...
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